Method of and apparatus for twisting yarn

ABSTRACT

A yarn bobbin or package is rotated at high speed about an axis and the air immediately surrounding the bobbin is confined with an open-ended tube that is rotated with the yarn bobbin and projects beyond the yarn bobbin. This tube forms a vortex of air at its open end which has a velocity which decreases axially away from the package. The yarn is pulled off the bobbin toward this open end and passed through an eye axially spaced from the yarn bobbin so that this yarn is guided through the vortex to form a balloon. The air currents in the vortex brake the thread. The eye can be mounted well above the assembly, or can be provided in a recess in an insert received in the top of the yarn package. Offsetting this eye to the rotation axis of the yarn body causes a tension vibration to be formed in the yarn that prevents the snapping of the yarn during twisting thereof.

Hamel Mar. 11,1975

METHOD OF AND APPARATUS FOR TWlSTlNG YARN [75] Inventor: Edmund Hamel, Romanshorn,

Switzerland [73] Assignee: Die Evolution S.A., Rorschach, St.

Gallen, Switzerland [22] Filed: Feb. 22, 1974 [21] Appl. N0.: 444,714

[30] Foreign Application Priority Data Feb. 28, 1973 Germany l 2310002 Nov. 5, 1973 Germany 2355193 [52] US. Cl 57/59, 57/116, 57/156 [51] Int. Cl DOlh 7/00 [58] Field of Search 57/34 R, l R, 59, 116, 57/156, 106

[56] References Cited UNITED STATES PATENTS 2,011,481 8/1935 Getchell 57/59 2,064,270 12/1936 Rowe 2,186,525 1/1940 Getchell 2,843,998 7/1958 Schlums 57/59 3,444,680 5/1969 DeRuddcr et a1. 57/59 Primary Examiner-Donald E. Watkins Attorney, Agent, or Firm-Karl F. Ross; Herbert Dubno [57] ABSTRACT A yarn bobbin or package is rotated at high speed about an axis and the air immediately surrounding the bobbin is confined with an open-ended tube that is rotated with the yarn bobbin and projects beyond the yarn bobbin. This tube forms a vortex of air at its open end which has a velocity which decreases axially away from the packageThe yarn is pulled off the bobbin toward this open end and passed through an eye axially spaced from the yarn bobbin so that this yarn is guided through the vortex to form a balloon. The air currents in the vortex brake the thread. The eye can be mounted well above the assembly, or can be provided in a recess in an insert received in the top of the yarn package. Offsetting this eye to the rotation axis of the yarn body causes a tension vibration to be formed in the yarn that prevents the snapping of the yarn during twisting thereof.

18 Claims, 8 Drawing Figures METHOD OF AND APPARATUS FOR TWISTING YARN FIELD OF THE INVENTION The present invention relates to a method of and ap- BACKGROUND OF THE INVENTION A yarn is usually twisted by rotating a bobbin wound with the yarn at high speed on a driven spindle. The yarn is pulled off the package parallel to its rotation axis so that the twist imparted to the yarn is proportional to the velocity at which it is pulled off, in units of length per units of time, divided into rotation speed, in turns or revolutions per unit of time.

In general the yarn package is surrounded by a tube defining an axially extending space around the yarn package. The tube is closed and formed with an axially centered eye at one end, and the yarn is pulled out through this eye so that it forms a so-called balloon in the space between the yarn package and the inside of the tube. Clearly in such a structure the air in the space between the tube and the yarn package rotates with the assembly, so that wind resistance on the yarn in the balloon is minimal. The tension in the yarn as it is pulled off the spool is dependent mainly on the type of balloon. With the above-described system the characteristics of the balloon are determined mainly by the withdrawal speed of the yarn and the rotation rate of the yarn package. Since these two must bear a definite relationship to one another it is difficult, therefore, to control the thread tension.

The tension in the withdrawn yarn generally increases and decreases sinusoidally as a result ofthe way in which the yarn is wound on the yarn package. As a rule the thread forms a spiral which lies on the inside of the surrounding tube as a result of centrifugal force. In some situations it is possible, due to the variations in tension in the string caused by the way in which it is wound on the package, for the tension to peak at levels sufficient to break the filament.

OBJECTS OF THE INVENTION It is therefore an object of the present invention to provide an improved method of and apparatus for twisting a yarn.

Another object of this invention is the provision of an improved yarn-twisting system wherein the yarn tension can be controlled, without the danger of breaking the yarn.

Yet another object of this invention is to provide an improved method of and apparatus for twisting the yarn which overcomes the above-given disadvantages.

SUMMARY OF THE INVENTION These objects are attained according to the present invention in a system wherein a yarn package is carried on a spindle rotated at high speed about its longitudinal axis. A tube concentric with the axis has an open end and forms a cup completely spacedly surrounding the yarn package with its rim lying axially beyond the end of the yarn package. A takeup eye or guide is provided adjacent this end ofthe assembly but is spaced from the end of the tube, and generally centered on the rotation axis of the tube and yarn package. Thus the yarn is pulled off the yarn package to form a balloon which extends axially beyond the end of the bobbin up to the takeup eye. In this manner there is formed within the tube a body of air which rotates with the yarn package. and above the tube, between it and the takeup guide, there is formed a vortex having a rotation speed which decreases away from the yarn package. Pulling the yarn through this vortex brakes it effectively and therefore tensions the yarn to an extent which is determined by the distance between the guide and the upper rim of the tube, this distance determining the position of the yarn in the vortex. The yarn package lies below the rim of the tube or shell so that initially the yarn is drawn off. Through a body of air rotating with the bobbin and the shell, and is thereafter drawn through an air vortex with axially decreasing air velocity.

In accordance with another feature of this invention there is provided at the end of the yarn package corresponding to the open end of the tube a plate which rotates with the tube and the yarn package and which partially closes this end, defining with the tube an annular gap in which the balloon is formed. This plate or disk partitions the interior of the sleeve into an inner chamber in which the air rotates with the sleeve and the bobbin, and an outer chamber in which the vortex begins. In general the vortex may be considered to form in the region within the rim of the sleeve immediately above the spool. However, when the plate or disk is provided, the vortex begins to form immediately thereabove.

According to a further feature of the invention there is provided at the open end of the tube, that is at its rim, means for increasing or decreasing axial length of the tube at this end, and for decreasing and increasing the diameter of the tube at this end. This means is formed by an insert axially displaceable within the open mouth of the tube. In accordance with a further feature of the invention there is provided within the tube at the open end thereof an insert fitted to the yarn bobbin and having an upper surface formed as a surface of revolution centered on the rotation axis of the yarn bobbin. The center of this insert is formed with a recess in which is received a fixed eye.

According to another feature of the invention this eye is offset, that is eccentric, to the axis of the package. In this manner tension in the yarn between the eye and the bobbin is continuously sinusoidally increased and decreased within limits so as to counteract the normal increases and decreases in tension in the yarn. This arrangement has proven itself extremely effective in eliminating yarn breakage.

The open-ended tube surrounding the yarn bobbin according to the present invention extends somewhat beyond the bobbin, by 0.25 D to 0.75D, preferably 0.3D to 0.5D where D is the internal diameter of the tube at this end. This construction is responsible for the vortex which is created at the open end of this tube. The vortex generally is conical and extends axially toward the guide eye through which the yarn is withdrawn. The peripheral speed of the air in this vortex de creases axially away from the yarn bobbin. As the yarn is pulled through this vortex it is naturally braked in a manner which has proven extremely effective in controlling the tension therein. The distance between the guide eye and the yarn bobbin determines the extent to which the yarn passes through this vortex, and therefore determines the level of tension in the yarn, since the-swirling air naturally brakes the yarn.

BRIEF DESCRIPTION'OF THE DRAWING The above-and other objects, features, and advantages of the present invention will become readily apparent-fromthefollowing description, reference being SPECIFIC DESCRIPTION As shown in FIGS. 1 and 2 a yarn package or bobbin 12 comprises a cylindrical body 18 of yarn 26 received between two end discs 14 and 16. This bobbin 12 is carried on a shaft rotatable by a motor 11 in the direction shown by arrow 13. An inner tube 20 spacedly surrounds the cylindrical yarn bobbin l2 and has one end 21 which is open and another end closed by a wall 23 secured to the shaft 10. This tube 20 therefore forms a space 24 surrounding the yarn package and the open end 21 of the tube 20 extends a distance d beyond the end 14 of the yarn bobbin 12. The tube 20 has an inner diameter D equal to approximately 4d. An outer tube 22 coaxial with and slightly longer than the inner tube 20 is carried on a fixed journal 25 and forms a space 30 surrounding the inner tube 20. Thus air currents generated by tube 20 will not interfere with neighboring assemblies. An eye 28 is located above the assembly in line with the axis A thereof and is vertically adjustable by fixed clamp 19. The yarn 26 is drawn off the body 18 and up through the eye 28 in the direction shown by arrow A and is then wound onto a takeup spool 27 rotated by a motor 29.

On rotation by the motor 11 the yarn bobbin 12 and the tube 20 form a conical vortex V having a velocity V, at its upper end which is substantially less than the velocity V at its lower end. Thus the yarn 26 forms a balloon 32 which passed through this vortex V and which is therefore braked by this vortex. The position of the balloon 32 in the vortex is determined by the vertical position of the eye 28 relative to the assembly.

FIG. 3 shows an assembly wherein a yarn bobbin 12a has a yarn body 180 which is tapered in both axial directions. A disk 14a is provided on the top of this yarn bobbin 12a so as to define a narrow gap with the inside of the tube 20. The balloon 32 is formed within this gap 15.

FIG. 4 shows an assembly identical to that of FIGS. 1 and 2 with the exception that an insert 34 formed as a cylindrical sleeve or collar is received within the open end 21 of the tube 20. This construction increases the distance d to a distance d which is substantially twice as great, while decreasing the diameter 35 of the tube at its open end substantially. Thus a tighter but higher vortex V is formed.

The reference numerals of FIGS. 1 and 2 are used for FIGS. 5-8 wherever the structure therein is identical.

In the arrangement of FIG. 5 there is provided at the upper end of the yarn bobbin 12 an insert 41 having a cylindrical center section 40 wedged into the top of the bobbin and coaxial with the axis A thereof and a skirt 36 which is formed as a surface of revolution centered on the axis A and having the natural shape assumed by the yarn 26 as it passes up around the package 18 in the space 24. In addition there is provided within this central portion an eye 28a having a lower end below the open end of the tube 20 and below the upper end of the insert 41. This eye 28a is fixed rotationally by an external clamp 43.

The arrangement of FIG. 6 is identical to that of FIG. 5 with the exception that the insert 41' here has a skirt 38 of rectangular section and having an outer edge, like the skirt 36, in line with the outer edge of the upper end 14 of the yarn bobbin. The arrangements shown in FIGS. 5 and 6 are useful with tightly twisted yarn which frequently untwists right back to the yarn body 18 and cause so-called wind-ups.

It is possible in accordance with the present invention to use a hollow spindle 10 and wind the yarn 26 around a core filament as indicated at 37 in FIG. 6. Furthermore this axis 10 can be vertical as shown with the open end 21 of the tube 20 directed upwardly, or it can be mounted horizontally or at an angle. It is also possible according to the present invention to use the abovedescribed systems for two-step twisting operations. In these arrangements Z, S, S, and Z, Z, S twists are created. The former is a twisting arrangement wherein the threads forming the yarn have a right-hand twist and are twisted in the first as well as in the second steps to the left. The latter arrangement uses threads with a right-hand twist and the first step uses right-hand twist and the second step left-hand twist.

FIGS. 7 and 8 show systems similar to that of FIG. 6, with the exception that here the eye 28b is offset from the axis A by a distance a. This eye 28b is fixed so that with each rotation of the bobbin 12 the radial component of the thread 26 between the location from which is pulled off the body 18 and the eye 28b will decrease continuously from a minimum distance x to a maximum distance y. This continuously changing radial length causes the yarn 26 to be pulled off the package with a sinusoidally varying tension. The filament is shown at solid line 26 in FIG. 7 in the relatively loose position it assumes when it is being pulled off the upper portion of the body 18. Dashed line 26' shows the relatively tight position it assumes when it is being off the lower portion of the body 18. The vibration set up in the filament 26 by the fixed off-center eye 28b is very effective to eliminate the differences in tension caused by the position on the yarn package from which the yarn is pulled.

I claim:

1. A method of twisting a yarn comprising the steps of:

rotating a yarn bobbin about an axis;

confining the air immediately sourrounding said bobbin with an open-endedtube rotatable therewith about said axis and projecting therebeyond to generate a vortex of air at the open end of said tube with a velocity decreasing axially away from said package; and

pulling a yarn off said bobbin and through an eye axially spaced therefrom and guiding said yarn through said vortex to form a balloon thereof in the confined air and said vortex.

2. The method defined in claim 1, further comprising the step of periodically varying the radial component of the length of the section of yarn between said bobbin and said eye.

3. A method of twisting a yarn comprising the steps of:

rotating a yarn bobbin about an axis;

confining the air immediately surrounding said bobbin with an open-ended tube rotatable therewith about said axis;

pulling a yarn off said bobbin and through an eye axially spaced therefrom and at least adjacent said axis such that said yarn travels axially and radially from said bobbin to said eye; and

periodically varying the radial component of travel of said yarn between said bobbin and said eye.

4. The method defined in claim 3 wherein said component is varied by positioning said eye fixedly eccentrically to said axis.

5. An apparatus for twisting a yarn comprising:

a spindle having a longitudinal axis and adapted to receive a yarn bobbin;

a tube concentric with said axis and fixed on said spindle, said tube defining an axially extending space with said bobbin and having an axially open end projecting beyond said bobbin;

means for rotating said spindle, said bobbin, and said tube about said axis and thereby generating a vortex of air at said open end of said tube and having a velocity decreasing axially away from said pack age;

an eye axially spaced from said bobbin at said open end; and

means for pulling a yarn off said bobbin and through said eye and guiding said yarn through said vortex to form a balloon thereof in said space and in said vortex.

6. The apparatus defined in claim 5 wherein said eye is rotationally fixed relative to said tube and spindle.

7. The apparatus defined in claim 6 wherein said eye is offset from said axis.

8. The apparatus defined in claim 6 wherein said eye is displaceable along said axis, said apparatus further comprising means for clamping said eye along said axis.

9. The apparatus defined in claim 5, further comprising an end element secured to said spindle at said open end of said tube and defining with said tube an annular gap, said balloon being formed in said gap.

10. The apparatus defined in claim 9 wherein said element is a flat circular disk overlying said bobbin.

11. The apparatus defined in claim 9 wherein said element is formed with a surface of revolution centered on said axis and formed at said axis with a recess, said eye being located in said recess.

12. The apparatus defined in claim 11 wherein said eye is positioned in said recess offset from said axis.

13. The apparatus defined in claim 11 wherein said surface is curved in cross section corresponding to the shape of said balloon.

14. The apparatus defined in claim 11 wherein said surface is generally rectangular in cross section.

15. The apparatus defined in claim 5, further comprising means for displacing said open end of said tube axially relative to said bobbin.

16. The apparatus defined in claim 5 wherein said tube is formed of a main tube section and said means for displacing said end includes an insert collar carried on the end of said tube section and forming said open end, said collar being displaceable in said section.

17. The apparatus defined in claim 5, further comprising a fixed tube coaxial with the first-mentioned tube and surrounding same.

18. The apparatus defined in claim 5, wherein said tube is generally cylindrical, said tube projecting beyond said bobbin by a distance equal to between 0.25

and 0.5 of the diameter of said tube. 

1. A method of twisting a yarn comprising the steps of: rotating a yarn bobbin about an axis; confining the air immediately sourrounding said bobbin with an open-ended tube rotatable therewith about said axis and projecting therebeyond to generate a vortex of air at the open end of said tube with a velocity decreasing axially away from said package; and pulling a yarn off said bobbin and through an eye axially spaced therefrom and guiding said yarn through said vortex to form a balloon thereof in the confined air and said vortex.
 2. The method defined in claim 1, further comprising the step of periodically varying the radial component of the length of the section of yarn between said bobbin and said eye.
 3. A method of twisting a yarn comprising the steps of: rotating a yarn bobbin about an axis; confining the air immediately surrounding said bobbin with an open-ended tube rotatable therewith about said axis; pulling a yarn off said bobbin and through an eye axially spaced therefrom and at least adjacent said axis such that said yarn travels axially and radially from said bobbin to said eye; and periodically varying the radial component of travel of said yarn between said bobbin and said eye.
 4. The method defined in claim 3 wherein said component is varied by positioning said eye fixedly eccentrically to said axis.
 5. An apparatus for twisting a yarn comprising: a spindle having a longitudinal axis and adapted to receive a yarn bobbin; a tuBe concentric with said axis and fixed on said spindle, said tube defining an axially extending space with said bobbin and having an axially open end projecting beyond said bobbin; means for rotating said spindle, said bobbin, and said tube about said axis and thereby generating a vortex of air at said open end of said tube and having a velocity decreasing axially away from said package; an eye axially spaced from said bobbin at said open end; and means for pulling a yarn off said bobbin and through said eye and guiding said yarn through said vortex to form a balloon thereof in said space and in said vortex.
 5. An apparatus for twisting a yarn comprising: a spindle having a longitudinal axis and adapted to receive a yarn bobbin; a tuBe concentric with said axis and fixed on said spindle, said tube defining an axially extending space with said bobbin and having an axially open end projecting beyond said bobbin; means for rotating said spindle, said bobbin, and said tube about said axis and thereby generating a vortex of air at said open end of said tube and having a velocity decreasing axially away from said package; an eye axially spaced from said bobbin at said open end; and means for pulling a yarn off said bobbin and through said eye and guiding said yarn through said vortex to form a balloon thereof in said space and in said vortex.
 6. The apparatus defined in claim 5 wherein said eye is rotationally fixed relative to said tube and spindle.
 7. The apparatus defined in claim 6 wherein said eye is offset from said axis.
 8. The apparatus defined in claim 6 wherein said eye is displaceable along said axis, said apparatus further comprising means for clamping said eye along said axis.
 9. The apparatus defined in claim 5, further comprising an end element secured to said spindle at said open end of said tube and defining with said tube an annular gap, said balloon being formed in said gap.
 10. The apparatus defined in claim 9 wherein said element is a flat circular disk overlying said bobbin.
 11. The apparatus defined in claim 9 wherein said element is formed with a surface of revolution centered on said axis and formed at said axis with a recess, said eye being located in said recess.
 12. The apparatus defined in claim 11 wherein said eye is positioned in said recess offset from said axis.
 13. The apparatus defined in claim 11 wherein said surface is curved in cross section corresponding to the shape of said balloon.
 14. The apparatus defined in claim 11 wherein said surface is generally rectangular in cross section.
 15. The apparatus defined in claim 5, further comprising means for displacing said open end of said tube axially relative to said bobbin.
 16. The apparatus defined in claim 5 wherein said tube is formed of a main tube section and said means for displacing said end includes an insert collar carried on the end of said tube section and forming said open end, said collar being displaceable in said section.
 17. The apparatus defined in claim 5, further comprising a fixed tube coaxial with the first-mentioned tube and surrounding same. 